crazyL Posted October 6, 2012 Share Posted October 6, 2012 (edited) tonyD, my L20a originally came with 78mm bore size, currently its bored .50 mm oversize, do you know what is the maximum bore I can bore it to? why I ask is cuz you said that you could fit the L24 83mm pistons in or the 86mm L28 pistons in! other Question is what are the strok diffrences between L20 - L24 - L28 ? and would an RB20DE crank fit into L series motor? my engine has died on me (rear seal leaking due to crank groove) and I'm planning to build something that will have power in it, before the leak I kept pushing the engine up to 6K-7K RPM for shifting. the head is "05L" it has been slightly shaved don't know how much though, the camshaft in it has E30 written on it Edited October 6, 2012 by crazyL Quote Link to comment Share on other sites More sharing options...
ClintM Posted October 9, 2012 Share Posted October 9, 2012 Im also curious about boring the l20a to fit l28 pistons,i have a l20et and a l28 block,i would like to fit the l28 pistons rod and crank from the l28 block into the l20 block,the reason for me doing this is because the l28 that i have is a rear bowl sump and wont work in a skyline. Quote Link to comment Share on other sites More sharing options...
ctc Posted October 9, 2012 Share Posted October 9, 2012 You might just want to make a new oil pick-up tube for the L28. It is consideraly less work than boring a block. I have an L28ET in my Skyline that I coverted to front sump. We now return you to the L20 thread you were reading. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 9, 2012 Share Posted October 9, 2012 tonyD, my L20a originally came with 78mm bore size, currently its bored .50 mm oversize, do you know what is the maximum bore I can bore it to? why I ask is cuz you said that you could fit the L24 83mm pistons in or the 86mm L28 pistons in! other Question is what are the strok diffrences between L20 - L24 - L28 ? and would an RB20DE crank fit into L series motor? my engine has died on me (rear seal leaking due to crank groove) and I'm planning to build something that will have power in it, before the leak I kept pushing the engine up to 6K-7K RPM for shifting. the head is "05L" it has been slightly shaved don't know how much though, the camshaft in it has E30 written on it Stock bore is 78, L24 bore is 83. That's about max on the early bores with the thick walls. Sonic testing is in order. The RB20 is a different animal altogether. A Crank groove is not the end of the world, put a Speedy-Sleeve on it and you're set. Don't even have to pull the engine to do that repair! The L20A is a revbeast. Bigger bores only increase that tendency! Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 9, 2012 Share Posted October 9, 2012 (edited) Even more, look at the FSM's fuel consumption curves. You'll get better milage, stock-for-stock, by cruising at 3000-3700RPM, than you will at 2500-2800RPM. Might also read around here on the "VE Valley" that stock engines map out with on megasquirt, even though we don't really know *why* it happens yet. Can you specify which manual you found this in? I'd like to look at that, as fuel consumption in general favors lower rpm operation as the applied torque is a greater percentage of available torque, lowering the BSFC. I've been driving my Toyota truck with a 22RE below 2000 rpm and am constantly rewarded with 30+ mpg on a tank by tank basis. Edited October 9, 2012 by SleeperZ Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 9, 2012 Share Posted October 9, 2012 A 22RE is NOT an L20A! The 22RE is / was designed as an industrial refrigeration plant, and optimized at exactly that power range (22-2400, as most petrol power plants are when run 24/7...) You will find that running the engine there instead of at 1800 will not cause a considerable change in consumption at all. It comes down to oil flow and pressure in the bearings for me. Lugging an engine like that puts loads that aren't nice on the bearings, detonate and with low oil pressure you jump the wedge and scuff the bearing, or catch it... The engine operated at 2200 would not stand NEARLY as high a probability of this happening. That being said, the owners manuals in Japan contained this information. If I can get the time, I will shoot the one from the L20A FSM I have, or the 77 Fairlady Z Owner's manual. The VW manuals also had these same fuel consumption/gearing curves in them. Water cooled engines are tolerant of this far more than air cooled. The Japanese Taxi Drivers made driving on detonating engines an artform. How quickly after into the next gear could you get audible ping. It seemed it was continuous. 30KPH and already in 5th in an LPG Powered L20A... For the acceleration needed, just gas it, knock like crazy and accelerate leisurely... Nissan made durable stuff. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted October 9, 2012 Share Posted October 9, 2012 (edited) I understand I made a generalized statement based on a different engine, that's why I'm curious to see the graphs. I don't detonate or lug my 22RE, if I need to accelerate more quickly I gear down; otherwise just cruising I can be in 4th at 30mph and 5th at 45mph (4.10 diff, 235/75/15 tires). If it was detonating I imagine that would probably result in poorer mileage, rather I am operating it nearer to it's torque limit at that RPM, and that equates to higher thermal efficiency on the BSFC chart. Edited October 9, 2012 by SleeperZ Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 10, 2012 Share Posted October 10, 2012 I probably should have clarified about the 22RE and 18R series of Toyota Engines, their head design is really detonation tolerant. They really like being lugged. Then again, I took out all the bearings in my 18R as well, so maybe that colors my memory a bit! Quote Link to comment Share on other sites More sharing options...
Xnke Posted October 10, 2012 Share Posted October 10, 2012 (edited) Realistically the point about the fueling curves is very likely cam related, more than anything. You can drive my car in 4th at 30MPH and it's fine...1800RPM. Due to the exhaust leak at the manifold flange though, you can definitely tell the engine is working harder...and the megasquirt display is showing much reduced intake vacuum and higher fueling for the same AFR's. Punch the throttle and it is slow to pick up RPM's, but it will pull itself along. Same 30MPH, 3rd gear, 2200RPM...higher vaccum, lesser fueling, same AFRs...engine is producing more torque and more RPM's...more than needed. So the amount of work being done is less than the amount of power available to use it. I am not sure on the werkin's of this mathematically; but I do know that driving in *my* car, with *my* cam, and *my* headwork, the car returns the best mileage at 2500-2900RPM. Tip it over to 3100 and mileage goes to **** and smilage goes waaayyy up. Drive the car under 2500RPM and it's generally happy down to about 1800...but fuel mileage suffers. Edited October 10, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted October 10, 2012 Share Posted October 10, 2012 My 1981 C21 Laurel Medallist I had in the early '00s with the L20E would cruise at 100Km/H at around 3500 to 3700 revs, and returned around 10 litres to the 100 Km. Quite respectable fuel mileage for an early 80's car with a 70's tech engine. The 1985 Toyota Surf (4-runner stateside) with the 3Y-J was geared to cruise at 100km/h at 2800-3000. Different makers, different philosophies. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 10, 2012 Share Posted October 10, 2012 (edited) Many of the English Magazines were obsessed with 5th gear pulling power. Their test was to put the car into 5th and make a WOT Pull from 1,000 rpms. The L-6 would do it. It's still a valid test for power curve testing and setup for both carbs and EFI. I just got some time bought since there are no utilities to the site I was supposed to be flying to tomorrow (er, today...) and I can see if I can snap those curves and upload them. I BELIEVE there is at least ONE set already up on this site: the LD28, from the JESCO LD28 Flyer. Edited October 10, 2012 by Tony D Quote Link to comment Share on other sites More sharing options...
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